Classic Machines: The Allis-Chalmers HD-5

Allis-Chalmers always had a good reputation for making reliable and versatile track type tractors, but its new HD-5 introduced in 1946 exceeded all expectations. By Richard Campbell

In the company’s search for new machines to replace existing pre-WWII designs, which by then were quite outdated, Allis-Chalmers came up with a whole new range of track type tractors that started in 1946 with the subject of this month’s article – the model HD-5.

Design work on the HD-5 had begun in early 1945 when it was pretty clear that the Allies had the war well under control and restrictions on new research and development for domestic products had been relaxed.

The HD-5 replaced the model M and WM in Allis-Chalmers’ range of tractors and was an all-new design.

Utilising the General Motors 2-71 diesel engine the output of the new HD-5 was around 48 horsepower.

Allis-Chalmers had begun using GM Diesels prior to WWII as its ‘standard’ diesel engine.

Allis-Chalmers did not at that time produce a reliable diesel engine of its own.

GM diesels were fitted to the HD-5, HD-7, HD-9, HD-10, HD-14, HD-15, HD-19 and HD-20 and all of them were ‘71’ series models of various types apart from the HD-20 that used a model 6-110.

The GM engine had a proven record of reliability, was reasonably economical to run, spare parts were plentiful, and, as they had been fitted to a plethora of other equipment both civil and military, there were legions of people who knew how to fix them.

Weighing in at around five tons bare, the HD-5 had a five-speed, one reverse, sliding gear manual transmission with a single plate dry clutch.

Unusually for the time, it had double reduction final drives which, as the gears were smaller, allowed a greater ground clearance under the tractor.

This made the tractor popular for land clearing operations as there was less likelihood of the machine getting ‘hung up’ on stumps and boulders. The HD-5 proved ideal for agricultural work.

Available in two track gauges, 60 inch and 44 inch, the HD-5 used the same length track frame in either case.

The 44 inch gauge model was occasionally referred to as the HD-5A while the 60 inch gauge version was known as the HD-5B.

Track frames were just under five and a half feet long and pinned at the rear, which allowed track frame oscillation. A solid equalizer bar was fitted.

There were four bottom rollers and one carrier roller per track frame.

Usual track shoe was a 13-inch single grouser type, 33 per side.

Allis-Chalmers had always been responsive to operator comforts and the HD-5 was no exception. A deeply padded seat and armrests were provided along with a full set of instrumentation.


Allis-Chalmers offered very little in the way of creature comforts for its HD-5. There was a sun canopy, but no cab or heater (it was the early 1950s after all) and the only other options available were various lighting packages for night operation and a cold starting kit for winter.

As Allis-Chalmers at that time did not manufacture its own work tools, it was up to its many ancillary suppliers to outfit the HD-5 for the work it was intended to do.

Principal supplier of bulldozer blades was the Baker Company who produced both straight and angle blades for the HD-5.

These were hydraulically controlled by two, double acting cylinders.

Early Baker blade installations had the two cylinders working on a vertical frame as had been done with previous A-C dozers such as the HD-7 and HD-9.

However, this arrangement was found to be a bit cumbersome for the HD-5 and a brand new design was fitted with the two lift cylinders gimbal-mounted to either side of a new solid nose cone that also housed the hydraulic pump.

Baker was not the only supplier of blades as both Carco and GarWood also offered dozer blades for the HD-5.

GarWood’s arrangement did not require the addition of a new solid nose, as it utilised hydraulic cylinders mounted on a bracket attached to the track frame (a la Bucyrus-Erie) with its hydraulic pump driven from the rear of the engine’s Power to Take-off (PTO).

This setup, however, left little room on the rear of the tractor for anything else.

Carco’s blade setup was a little more complex and featured a whole new front radiator guard.

It was very rare to see an HD-5 with a cable operated blade or, indeed, a rear PCU although the Buckeye Corp did manufacture a double drum unit for the HD-5 for pulling small cable operated scrapers.

But the vast majority of HD-5s used for towing a scraper had a hydraulically operated unit.

For logging, or recovery operations, the most common winch seen on an HD-5 was a Carco Model E that had a bare line pull of some 18,600 lbs.

The HD-5 Loader & Tractomotive Corporation

Tractomotive manufactured a complete, dedicated track loader package for the wide gauge (60 inch) Allis-Chalmers HD-5 called the TS5 which permanently turned the machine into a track-type loader.

Although no production records are available for this conversion, as machines were allocated directly off the tractor production line, Allis-Chalmers sold thousands of them and they were known as the HD-5G.

They were an ideal size for the small contractor doing basements, small demolition jobs or landscaping, or for larger contractors requiring a machine for cleanup work.

With a slightly longer track frame containing an extra bottom roller, and mounting a one cubic yard bucket, the HD-5G was also a ground breaker in being one of the first hydraulic track loaders to feature hydraulic roll-back, or crowding of the bucket, which is something commonplace these days.

Conversion of the HD-5 to an HD-5G also usually included replacing the single bar grouser track shoes with triple bar shoes that allowed easier turning and less ground disturbance, but not all HD-5Gs had this modification.

The first HD-5 loaders were available from 1948 and remained in production until 1955.

A fully equipped HD-5G ready for action weighed around eight and a half tons.

In summary, the Allis-Chalmers HD-5 was a very successful machine with over 29,000 of them manufactured during the period 1946 through to 1955 and paved the way for its successor – the fantastic little HD-6.

The New Zealand connection

We embraced the little HD-5 and hundreds were sold here although, unfortunately, no records of the actual numbers imported survive.

Both 40-inch and 60-inch gauge models were sold here, along with the Tractomotive loader conversion – the HD-5G.

Due to the machine’s simplicity, quite a few have survived and are about to be, or have been, restored.

For the model collector

While there are no models in 1:50 scale of the Allis-Chalmers HD-5, in the late 1940s an American promotional company called Product Miniatures produced an HD-5 to approximately 1:16 scale with a Baker Hydraulic S-Blade and rubber tracks.

It was also available without the blade for those with an agricultural bent.

Made of plastic, the model isn’t actually too bad and is reasonably accurate in shape and layout.

Being old, it is now somewhat of a collectors’ item and good examples change hands for sums in excess of US$400.

They can occasionally be found on Ebay.

Brief Specifications – 1950 Allis-Chalmers HD-5

 Engine:  Two-cylinder General Motors 2-71 two cycle diesel engine rated at 41 flywheel horsepower at 1800 rpm

Clutch:                        Single plate overcentre, Borg & Beck

Transmission:           Five-speed manual sliding gear transmission with one reverse range

Speed Range:              1.4 to 5.7 mph

Steering:                      Conventional multiple plate steering clutches with dry, contracting band brakes each  side

Track Gauge:              HD-5A 44”, HD-5B 60”

Track Frame:              Four roller with one carrier roller per side*

*HD-5G – Five roller with one carrier roller per side

Std.Track Shoe:          13” single grouser

Length (bare):             10’ 3”

Width (bare):              6’ 5” (60” gauge version)

Height (bare):             6’ 10”

Weight (bare):             5.6 tons (60” gauge), 5.2 tons (44” gauge)





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